The field of the invention is apparatus for electroplating substrates, such as silicon wafers and similar substrates, and power supplies and controllers providing electrical power to electrodes in substrate electroplating apparatus.
In manufacturing micro-scale semiconductor and similar devices, process control equipment must meet requirements that are more demanding in comparison to most other industries. This results primarily because process parameters must be very closely controlled to successfully manufacture microelectronic devices. For example, in certain applications, it is important that a metal layer plated onto a substrate have uniform thickness over all areas of the substrate. Achieving a uniform plating profile or thickness requires precise control of electrical current provided via electrodes in the electroplating apparatus.
Electroplating apparatus in semiconductor manufacturing have used control systems similar to those used in other plating industries. Generally, these control systems include a combination of analog circuitry, and micro-controllers, or DSPs (digital signal processors), to read process parameters and close the feedback loop, allowing the system to produce the desired plating profile. These known control systems have met with varying degrees of success. Accordingly, there is a need for improved control systems and control methods.